Alkali hydroperoxides as olefin polymerization catalysts



United States Patent ALKALI HYDROPEROXIDES AS OLEFIN POLY- MERIZATION CATALYSTS Hugh 1. Hagemeyer, Jr., Kingsport, Tenn, assignor t0 Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application August 13, 1953, Serial N 0. 374,147

7 Claims. (Cl. 260--94.9)

This invention relates to a novel process for the manufacture of polymers and interpolymers from olefins. More particularly, this invention relates to the polymerization of ethylene, and the interpolymerization and telomerization of ethylene with one or more compounds.

It is well known that ethylene can be polymerized with the aid of catalysts such as dialkyl dioxides, acyl peroxides, oxygen, Chloramine-T, manganese dioxide, amine oxides, tetraphenyl tin, tetraphenyl lead, tetraethyl lead, butyl lithium, hexachloroethane, sodium perborate, sodium persult'ate, potassium chlorate, hydrazine and azo compounds and other typical polymerization catalysts. However, these catalysts have many shortcomings. For instance some catalysts may contaminate the ethylene polymer with an inert inorganic residue which impairs its excellent electrical properties and the heat stability of the ethylene polymer, or it may give an ethylene polymer of limited solubility and melt extrudability. Many of the previously known peroxide catalysts are disadvantageous in that they tend to cause the polymerized material to discolor and to produce polymers with lower average molecular weights. In addition, most of the prior art organic peroxide catalysts are not sufficiently stable at the elevated temperatures required to polymerize ethylene to be used efliciently in an ethylene polymerization process. The most stable form of organic peroxygen compounds is the class known as the hydroperoxides, and particularly that class of hydroperoxide which constitutes an aryl (dialkyl) methyl hydroperoxide. I have now found that the alkali metal salts of the hydroperoxides are particularly advantageous in the polymerization of ethylene and in the preparation of ethylene interpolymers.

Accordingly, it is an object of my invention to provide a novel process for the manufacture of polymers and interpolymers from olefins. Another object is to provide a process for the manufacture of polymers and interpolymers from ethylene. Still another object is to provide a method of making telomers from ethylene and another organic compound. Other objects will become apparent from a consideration of the following description and examples.

According to my invention I realize the above objects by heating ethylene in the presence of an alkali metal or alkaline earth metal salt' of a hydroperoxide at temperatures ranging from 100 to 400 C. and pressures from about 100 to 3000 atmospheres (1470 to 44,100 p. s. i.'). A more limited temperature range which I have found to be particularlyuseful is from 100 to 300 C. The conditions of temperature and pressure utilized in my invention have been previously described in U. S. Patent 2,153,553.

One of the outstanding advantages of the alkali metal or alkaline earth metal salts of the hydroperoxides of my invention is that these salts are extremely heat stable with the result that there is negligible decomposition below the elevated temperature required for the polymerization of ethylene. This form of hydroperoxide catalyst is also completely soluble in Water, which means that a homoge- 2,772,259 Patented Nov. 27, 1956 neous polymerization wherein the monomer and the catalyst are both dissolved in water can be carried out. Thus the catalysts used in accordance with my invention permit homogeneous polymerizations at temperatures higher than those possible with previously known catalysts, thereby resulting in the formation of a more branched chain polymer which has greater flexibility and is particularly desirable for the formation of films. Furthermore, the polymers produced using the alkali metal or alkaline earth metal salts of the hydroperoxides are of considerably higher molecular weight than those prepared using prior art polymerization catalysts under comparable conditions. In addition, the polymers have much less tendency to discolor and are heat stable at elevated temperatures when prepared using the alkali metal or alkaline earth metal salts of the hydroperoxides as catalysts. Still another advantave realized with the catalysts of my invention is the fact that they provide a mildly basic solution without the use of additional buffers or alkali, which is particularly desirable in the homopolymerization of ethylene in the presence of water. The polymers of ethylene obtained according to my invention vary from greases or waxes in the molecular weight range of 1,000 to 6,000 to resinous materials having excellent solubility and melt extrusion characteristics with molecular weights in excess of 6,000. The polymers of ethylene obtained according to my invention are further characterized by having higher softening temperatures than the polyethylene usually obtained according to prior art methods.

The catalysts used in my invention can advantageously be represented by the following general formula:

R-OOM wherein R represents an alkyl group (e. g. t-butyl, t-amyl, benzyl, etc.) and M represents an alkali metal atom or an .alkaline earth metal atom (e. g. sodium, potassium,

wherein R1 and R2 each represents an alkyl group (e. g.

methyl, ethyl, etc.), R3 represents an aryl group such as a mononuclear aryl group of the benzene series (e. g. phenyl, tolyl, p-isopropylphenyl, p-(o et-dimethyl-u-hydroperoxy methyl) phenyl, etc.), and M has the values given above. The catalysts useful according to my invention can be prepared in the manner described in Dickey et al. U. S. Patent 2,403,709, issued July 9, 1946.

The polymerization of ethylene with an alkali metal or alkaline earth metal salt of a hydroperoxide can be carried out either as a batch, semi-continuous, or continuous operation, in which a suitable reaction vessel is charged with the catalyst and the polymerization medium, and then heated under superatomspheric pressure until the desired degree of polymerization is obtained.

The amount of catalyst employed can be varied, depending on the quantity of material being polymerized, the presence or absence of an inert liquid polymerization medium, temperature, etc. In general, I have found that an amount of catalyst varying from 0.0001 to about 12 percent by weight, based on the total weight of monomers charged to the reaction vessel, can be employed.

The polymerization can be carried out in the presence of inert diluents, such as water, t-butyl alcohol, cumene, toluene, methyl alcohol, n-butyl alcohol, etc., or mixtures of the aforementioned solvents. I have also found that it is sometimes advantageous to employ melted polyethylene itself as a diluent.

Vigorous agitation is generally employed in practicing the polymerization of ethylene according to my invention, since it is thus possible to maintain homogeneous reaction conditions and avoid local overheating. The heat of re- 4 with ethylene to 1000 p. s. i. After heating to 145 C. the pressure was raised to 4,500 p. s. i. and maintained by the addition of ethylene as required. Four hundred and seventy-five grams of a white, hard wax was obtained.

action can be removed by means of external cooling, such 5 Methanol, water, and dissolved ethylene were removed by methods being previously described in the prior art. The passing nitrogen through a wax melt. The final product reaction is advantageously carried out in a vessel conhad a density of 0.938, M. P. 103-4 C., and a molecular structed of or lined with a corrosion resistant material, weight of 4,300.

for example, stainless steel or silver. 1 l

The following examples will serve to illustrate more Example 5' Poyethylme lesm fully th manner h b 1 Practice h process of my Five grams of the dilithium salt of the dihydroperoxide invention. of p-diisopropyl benzene was suspended in 200 grams of molten ol ethylene (molecular weight 7,400), 130 C., Example 1.-P0lyethylene W and chai gec i to a one-liter stainless steel autoclave. Ethyl- A one-liter stainless steel autoclave was charged with ene was pressed in at 8,0009,000 p. s. i. while maintaining 500 grams of water containing 24 grams of the sodium a reaction temperature of 145 C. by cooling. The prodsalt of cumene hydroperoxide. The autoclave was heated uct yield was 612 grams of polyethylene with a molecular to 160162 C. and pressured with ethylene to 3,600 p. s. i. weight of 9,200. This included the 200 grams of beginning The polymerization was rapid and complete in 12 minutes polyethylene. and external cooling was required to maintain the reaction temperature in the range 160162 C. Two hundred and Example mtei'polyme" elght, grams h 3 h White mehlhg pom/E Two hundred and eight grams of styrene, 300 grams of dehslty lodlhe and molecular Welghe 3,200 butanol, and 50 grams of water containing 4 grams of the was obtained. In a similar run employing u Hydro N a salt of cumene hydroperoxide were charged to a one- Peroxlde and hS1hg,24 grams catalyst m 500 of liter stainless steel autoclave. The autoclave was purged methahoh "eaehoh was carried out at ahd and charged to 3,000 p. s. i. with ethylene and heated to 9 g huhdreh and Y' Y grams of awax 175 C. The pressure was raised to 9,000 p. s. i. with melting at 108 0., density 0.921, iodine No. 5.4, an ethylene and was maintained there by the addition of ethylmolecular weight 1,800 was produced. ene as required The above ruhshre ew for purheses of comparison The reaction was stopped at the end of 6 hours and 373 and the Obtalhed h the Sodlum l of e f grams of ethylene-styrene interpolymer was obtained, hydroperoxide was essentially colorless, and in addition to composition C H (C H CH:CHZ) (molar ratio). the high m Weight had a hardness, 0f The In a manner similar to that illustrated in the above exwax obtained using cumene hydroperoxide itself had a .amples, other polymerizable compounds can be p01y molecular weight of only 1,800, was a light tan in color, 5 mailed according to my invamiom For example, and had a hardness of 65-7" pounds containing monoethylenic unsaturation, i. e. compounds having the following group -CH:C can be Example Polyethylene wax advantageously employed in place of the ethylene illus- The following runs were made according to the process trated in the above examples. Further, the styrene emdescribed in Example 1 using the sodium and potassium ployed in Example 6 can be replaced with other polysalts of cumene hydroperoxide, and the disodium salt of merizable compounds. In addition to the ethylene and the dihydroperoxide of paradiisopropyl benzene. styrene illustrated, other compounds which can be em- Rim Catalysts Temp, Pressure, Product, M. 19., Density Iodine Molecular C. p. s. i. g. C. No. Weight .NaiHPDIPB... 100 3, 9004, 000 343 110 0. 918 5.4 4,400

.NazHPDIPB 100 3,000-as00 190 10s 0. 922 0.1 4, 300

.NaCHP 15s 3,000-3,s00 189 10s 0. 915 3.0 3,900

.KOH 105 3,000-3,900 20s 10s 0. 923 5.9 4,000

CHIP =cumeue hydroperoxide.

Example 3 .P0lyethylene resin A one-liter stainless steel pressure reactor was flushed with ethylene and charged with 5 grams of sodium cumene hydroperoxide in 200 grams of methanol. The reactor was charged with ethylene to a pressure of 300 atmospheres and heated to 160 C. Upon reaching this temperature, the ethylene pressure was raised to 1,000 atmospheres and the polymerization was allowed to proceed with agitation for a 24-hour period. As the ethylene polymerized the pressure was maintained at 900 to 1,000 atmospheres pressure by the addition of more ethylene. There was obtained 342 parts of a white solid ethylene polymer with a molecular weight of 28,000. The ethylene polymer obtained in this fashion was very tough and had a tensile strength of 3,200 pounds per square inch at 600% elongation, and was soluble to the extent of at least 40% by weight in xylene at 100 C.

Example 4.-Polyethylene wax The reactor of Example 1 was charged with 15 grams of the potassium salt of p-tertiary butyl dimethyl benzyl hydroperoxide dissolved in 500 ml. of an 80/20 methanol/ water solution. The autoclave was purged and charged ployed in practicing my invention comprise acrylonitrile, methacrylonitrile, ot-methyl styrene, methyl vinyl ketone, methyl isopropenyl ketone, vinyl pyridine, vinyl pyrrolidone, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, acrylamide, methacrylamide, M-methylacrylamide, M-methylmethacrylamide, etc. Also, diolefins such as butadiene, isoprene, etc. can be employed. As noted above, the catalysts of my invention can also be employed in telomerization processes wherein ethylene is employed, such as is illustrated in Hanford et al. U. S. Patent 2,402,137, issued lune 18, 1946.

What I claim as. my invention and desire secured by Letters Patent of the United States is:

1. A process which comprises heating ethylene in the presence of a catalyst selected from those represented by the following general formula:

wherein R1 and R2 each represents an alkyl group of from 1 to 2 carbon atoms, R3 represents a mononuclear aromatic group of the benzene series, and M represents an alkali metal atom, at a temperature of from about 145-175 C. and a pressure of about 200 to 1,000 atmospheres.

2. A process according to claim 1 wherein the process is carried out in the presence of an inert organic solvent.

3. A process according to claim 1 wherein the process is carried out in the presence of water.

4. A process which comprises heating ethylene in the presence of the sodium salt of cumene hydroperoxide at a temperature of from about 145-175 C. and a pressure of about 200 to 1,000 atmospheres.

5. A process which comprises heating ethylene in the presence of the potassium salt of cumene hydroperoxide at a temperature of from about 145-175 C. and a pressure of about 200 to 1,000 atmospheres.

6. A process which comprises heating ethylene in the presence of the disodium salt of the dihydroperoxide 6 of p-diisopropylbenzene at a temperature of from about 145175 C. and a pressure of about 200 to 1,000 atmospheres.

7. A process which comprises heating ethylene in the presence of the dilithium salt of the dihydroperoxide of p-diisopropylbenzene at a temperature of from about 145-175 C. and a pressure of about 200 to 1,000 atmospheres.

References Cited in the file of this patent UNITED STATES PATIENTS 2,450,451 Schmerling Oct. 5, 1948 2,462,680 Sargent Feb. 22, 1949 FOREIGN PATENTS 610,293 Great Britain Oct. 13, 1948 

1. A PROCESS WHICH COMPRISES HEATING ETHYLENE IN THE PRESENCE OF A CATALYST SELECTED FROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 